As an electrophotographic image forming apparatus, a color printer is known which includes four photosensitive drums for four colors, yellow, magenta, cyan, and black.
A color multifunction apparatus, which is proposed as an example of the color printer, may include process cartridges for each color, a support frame, an intermediate transfer belt and a secondary transfer roller. Each of the process cartridges may include a photosensitive drum and a developing unit. The developing unit may include a developing roller, a first supply roller, a second supply roller, a doctor blade, and a toner container. The support frame may be configured to integrally support the process cartridges arranged therein and to be pulled out toward a front side. The intermediate transfer belt may extend horizontally such as to contact the photosensitive drums from above. The secondary transfer roller may be disposed such as to contact the intermediate transfer belt from one horizontal direction.
In the above color multifunction apparatus, each process cartridge is detachably attachable to the support frame when the support frame is pulled out from the main casing toward the front side.
Each process cartridge may integrally include the photosensitive drum and the developing unit.
Typically, the photosensitive drum needs replacing with less frequency than toner refill. Thus, the demand to replace the developing unit only, without having to replace the photosensitive drum, is growing.
However, the photosensitive drum is supported by an upper end of the process cartridge and the developing unit is disposed under the photosensitive drum in the color multifunction apparatus.
Thus, it is difficult to move the developing unit only from or to the support frame up and down.